Hi,
Since you have recovered and going for regular check up, the 
bowel cancer will not have much effect. But what could have more effect is your age. At 45 years of age, the chances of 
pregnancy complication are much more.
There is  an increased chance of 
miscarriage, down syndrome in baby, congenital defects, 
hypertension in pregnancy, diabetes in pregnancy, preterm labour to name a few.
Also, if you do end up with a Caesarean, it might be a high risk surgery, as you have had previous surgery for 
colon cancer and adhesion are to be expected intra abdominally. This could make post operative recovery longer and difficult.
Please see a gynecologist who will carry out all basic checks to see your fitness for this pregnancies and exact dating of the pregnancy.
Hope this helps.
Regards.